ES2364397T3 - TIRES FOR HEAVY LOAD. - Google Patents

Abstract

A high performance tire characterized by using as tread rubber a rubber composition that is obtained by combining 100 parts by mass of a rubber component consisting of 90-30% by mass of (a) natural rubber and 10-70% by mass of (b) styrene-butadiene copolymer rubber polymerized in solution containing tin in at least one medium potion of the polymer molecular chain and one terminal of the molecular chain and having a bound styrene content of 28-45% by mass and a vinyl bond content in a portion of butadiene less than 30 mol% with 0.3-3.0 parts by mass of (e) a hydrazone compound and 40-60 parts in Total mass of (c) carbon black and (d) silica, provided that an amount of (d) silica as a load is 5-20 parts by mass.

Description

Technical Field

The present invention relates to a high performance tire and, more particularly, to a high performance tire that greatly improves its uneven wear resistance

Background of the Technique

So far, for the purpose of controlling uneven tire wear, various means have been used in the design of the tread grooves, in the shape of the tread crown, in the pattern of the tread pattern. rolling or the like, such as defense grooves and side grooves, and the like. However, these means present the problem that the control of uneven wear is insufficient. In general, non-uniform wear occurs in the ribs, studs and the like of the tire tread due to several factors before uneven wear occurs in the tire.

Since non-uniform wear of this type is due to pressure in the radial direction, pressure in a circumferential direction or a combined pressure in both directions with respect to a rotating direction of the tire, an attempt is made to improve the uneven wear resistance using a composition of rubber that is hardly affected at these pressures in a tread and combined with a tire structure.

In order to prevent uneven tire wear, a method is used that uses a rubber composition combined with styrene-butadiene copolymer rubber in the tread to increase the hysteresis loss. However, the combination of styrene-butadiene copolymer rubber impairs the heat accumulation of the tire, whereby there is particularly a restriction on the amount of combination of this in high performance tires.

Hereby, it is proposed to use polymerized styrene butadiene rubber in modified solution at a terminal of its polymer molecule to increase the dispersion of carbon black through a coupling effect of its modified terminal, whereby generation is improved of own heat to reduce heat accumulation to establish uneven wear resistance and heat accumulation (see, for example, JP-A11-217004, page 3). However, this is not enough for the high performance tire.

In addition, a technique is proposed to establish uneven wear resistance and heat accumulation by a combination of styrene-butadiene copolymer rubber polymerized in solution, silica and a silane coupling agent (see, for example, JP-A- 11-59116, page 1).

In JP 2002-146101, EP-A-1184412, US2001 / 0031795, US5856393 and EP0491229, rubber tires and rubber compositions for these are disclosed.

However, silica has such an effect that heat build-up does not decrease while increasing hysteresis loss, but under severe conditions of use it is feared that wear resistance in the high performance tire will decrease. In such a combination technique, uneven wear resistance and heat accumulation are in conflict relationship and it is difficult to establish them simultaneously.

Description of the Invention

Given the situation outlined above, the invention is carried out to solve the aforementioned problems and consists in providing a high performance tire that considerably improves uneven wear resistance without impairing heat accumulation and tire wear resistance.

The inventor has found that by combining the appropriate amounts of styrene-butadiene copolymer rubber polymerized in solution with a high cis content, silica and a specified hydrazone compound, in a rubber composition for a tire tread, the tire can be improved. loss of hysteresis while controlling the self-accumulation of heat of the rubber and uneven wear resistance can be improved without deteriorating heat accumulation and wear resistance and, as a result, the invention achieves its objective.

That is, the invention provides a high performance tire that is characterized by using as a tread rubber a rubber composition that is obtained by combining 100 parts by mass of a rubber component consisting of 90-30% by mass of (a) natural rubber and 10-70% by mass of (b) styrene-butadiene copolymer rubber polymerized in solution containing tin in at least one medium potion of the polymer molecular chain and one terminal of the molecular chain and which it has a bound styrene content of 28-45% by mass and a vinyl bond content in a butadiene portion of less than 30 mol% with 0.3-3.0 parts by mass of (e) hydrazone compound and 40-60 parts by mass in total of (c) carbon black and (d) silica, provided that an amount of (d) silica as filler is 5-20 parts by mass.

Best way to carry out the invention

As the component (a) of the rubber composition that is used in the tire according to the invention is natural rubber, but a part of the natural rubber can be replaced with polyisoprene rubber having the same structure as natural rubber.

The amount of (a) natural rubber is 90-30% by mass based on 100 parts by mass of the rubber component, preferably 60-40% by mass. When the amount of component (a) exceeds 90% by mass, there is no effect on uneven wear resistance, while when it is less than 30% by mass, it is difficult to maintain a low heat accumulation.

In the rubber composition used in the tire according to the invention, as component (b) styrene-butadiene copolymer rubber is used in solution containing tin in at least one medium potion of the polymer molecular chain and a terminal of the molecular chain and having a bound styrene content of 28-45% by mass and a vinyl bond content in a butadiene portion of less than 30 mol%.

The amount of (b) styrene-butadiene copolymer rubber polymerized in solution is 10-70% by mass based on 100 parts by mass of the rubber component, preferably 40-60% by mass. When the amount of component (b) is less than 10% by mass, the improvement effect on uneven wear is reduced, while when it exceeds 70% by mass, the fracture properties deteriorate considerably.

In addition, the styrene content bound in component (b) of the rubber composition that is used in the tire according to the invention is 28-45% by mass. When the content is less than 28% by mass, the effect of establishing uneven wear resistance and low heat accumulation is reduced, while when it exceeds 45% by mass, wear resistance deteriorates.

In addition, the vinyl bond content in component (b) is less than 30 mol%. When the content is not less than 30 mol%, the wear resistance decreases.

In component (b), a molecular structure of a reaction portion, which is formed by reacting a terminal carbanion of the hydrocarbon group linked to the styrene-butadiene copolymer obtained through an organolithium initiator consisting of a hydrocarbon and lithium group With a coupling agent or a modifying agent, it has a tin-carbon bond.

For example, the molecular structure of the reaction portion, which is formed by a stoichiometric reaction between a unilateral terminal carbanion of a styrene-butadiene copolymer bonded to a butyl group terminal obtained through a butyllithium initiator consisting in a butyl group as a hydrocarbon and lithium and tin tetrachloride group as a coupling agent, it has a structure in which four styrene-butadiene copolymers with butyl terminal are linked to tin, that is, a structure in which there is a bond tin-carbon in a middle portion of the final polymer.

When tributyl tin chloride is used as the modifying agent instead of tin tetrachloride in the previous embodiment, a final polymer having a tin-carbon bond structure is obtained at the other terminal of the styrene-butadiene terminal copolymer of the butyl group.

The above structure has an interaction with a filler such as carbon black or the like and is essential to improve the property of low hysteresis and wear resistance.

In addition, for the purpose of providing excellent properties, the average molecular weight before the modification reaction of component (b) is preferably 5x104-100x104, more preferably 10x104-100x104, and a molecular weight distribution is also preferred before the modification reaction of 1.0-1.3.

In addition, the production process of component (b) is not particularly limited as long as the molecular structure defined in the invention is obtained, but the copolymer of component (b) is easily obtained by the following procedure (which is disclosed in detail, for example, in JP-A-9-316132). The styrene-butadiene copolymer of component (b) is obtained by copolymerizing styrene and butadiene in a hydrocarbon solvent in the presence of (1) an organolithium initiator consisting of a hydrocarbon and lithium group, (2) at least one potassium compound selected from the group consisting of potassium alcoholate, potassium sulphonate and potassium carboxylate, and (3) at least one compound selected from the group consisting of ether compounds and amine compounds, and adding a tin compound as a modifying agent after copolymerization

As the hydrocarbon solvent, an aromatic hydrocarbon solvent such as benzene, toluene, xylene or the like can be used; an aliphatic hydrocarbon solvent such as n-pentane, n-hexane, n-butane or the like; an alicyclic hydrocarbon solvent such as methylcyclopentane, cyclohexane or the like; and a mixture of these, without particular limitations.

As organolithium initiator, alkyl lithiums, such as lithium metal, ethyl lithium, propyl lithium, n-butyllithium, secbutyl lithium, t-butyllithium, hexyl lithium, octal lithium, and the like are mentioned. ; aryl lithium, such as phenyl lithium, tolyl lithium and the like; and aralkyl lithium, such as benzyl lithium and the like.

Among them, n-butyllithium and sec-butyllithium are preferred from the point of view of industrial production. These organolithium initiators can be used alone or in combinations of two or more.

The amount that is added of said polymerization initiator is determined in accordance with the desired molecular weight of the copolymer, but is generally 0.05-15 mmol, preferably 0.1-10 mmol per 100 g of the monomer. When the amount exceeds 15 mmol, it is difficult to obtain a higher molecular weight, while when it is less than 0.05 mmol, polymerization cannot be performed.

As a randomizer a potassium compound, an ether compound and an amine compound are used. The term "randomizer" used herein means a compound that has the ability to increase the vinyl bond content in the butadiene portion of the styrene butadiene copolymer (this capacity is reduced in the potassium compound), a randomization of the distribution of composition of the butadiene unit and the styrene unit, and the like.

The potassium compounds used herein are potassium alcoholate, potassium sulphonate and / or potassium carboxylate. As potassium alcoholate there can be mentioned, for example, potassium t-butylate, potassium t-amylate, potassium ethylate, potassium isopropylate, potassium octylate, potassium dodecylate, potassium nonylphenylate and the like. Among them, considering the effect, potassium t-amylate and potassium nonylphenylate are preferred.

As potassium sulphonate, for example, potassium dodecylbenzene sulfonate, potassium naphthalene sulfonate and the like can be mentioned. Among them, considering the effect, potassium dodecylbenzene sulfonate is preferred.

As potassium carboxylate, for example, potassium stearate, potassium decanoate, potassium dodecanoate, potassium octoate, potassium naphtate and the like can be mentioned. Among them, considering the effect, potassium naphtate is preferred.

The amount of the potassium compound that is added is 0.01-0.2 mol equivalent to 1 mol of lithium, preferably the equivalent of 0.03-0.09 mol, considering the effect. When the amount is less than the equivalent of 0.01 mol, there is no effect as a randomizer, while when it exceeds the equivalent of 0.2 mol, undesirable side reactions such as metalation occur.

In addition, the ether compound and / or the amine compound are used together with the potassium compound. As the ether compound and / or the amine compound, compounds generally used as a randomizer can be used in the copolymerization of styrene and butadiene, without particular limitations. Among them, a dialkoxyalkyl compound such as diethoxy ethane or the like is preferably used; a diethylene glycol dialkyl ether compound such as diethylene glycol dimethyl ether, diethylene glycol diethyl ether or the like; an ethylene glycol dialkyl ether compound such as ethylene glycol dimethyl ether, ethylene glycol diethyl ether or the like; a tetrahydrofuran oligomer compound such as diterahydrofuryl propane or the like; tetrahydrofuran; a diamine compound such as tetramethylethylene diamine or the like; and a triamine compound such as pentamethylene diethylene triamine or the like.

Preferably, the amount of ether compound and / or amine compound that is added will be in an amount in which the vinyl bond content in the butadiene portion is not greater than 30 mol%. This amount is difficult to identify because it depends on the type of ether compound or amine compound, but is generally equivalent to 0.01-2.0 mol per 1 mol of lithium. For example, an appropriate amount when tetrahydrofuran is used is the equivalent of 0.5-2.0 mol and an appropriate amount when diethylene glycol dimethyl ether is used is equivalent to 0.03-0.1 mol.

In addition, the coupling agent or modifying agent is a tin compound. As the tin compound, for example, a tin halide such as tin tetrachloride or the like is mentioned; and an organic tin chloride compound such as butyltin trichloride, dibutyltin dichloride, dioctyltin dichloride, diphenyltin dichloride, tributyltin chloride, triphenyltin chloride or the like. It can be used in an amount such that an active terminal lithium of the styrene-butadiene copolymer is equivalent to a halogen atom

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fifteen

twenty

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30

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of the previous compound.

Among these compounds, tin tetrachloride, organic tin dichloride or the like contribute to a low hysteresis loss because it is subject to a coupling reaction with the active terminal of the styrene-butadiene copolymer to provide a coupled copolymer and the coupling efficiency not greater than 60%. In addition, the tin monochloride compound improves the loss of low hysteresis because it reacts with the active terminal lithium to provide a modified terminal copolymer.

Carbon black used in the tire according to the invention uses carbon black

(c) and silica (d) as filler. When preparing a carbon black compound, an effect to improve wear resistance can be obtained that causes an improvement in fracture resistance. The amount in the total composition of carbon black (c) and silica (d) is 40-60 parts by mass based on 100 parts by mass of the rubber component. When it is less than 40 parts by mass, wear resistance deteriorates, while when it exceeds 60 parts by mass, the low heat accumulation deteriorates.

The type of carbon black (c) is not particularly limited, but it can be arbitrarily selected from those generally used as fillers to reinforce conventional rubber. As carbon black (c) there may be mentioned, for example, FEF, SRF, HAF, ISAF, SAF and the like. Among them, SAF carbon black is preferred.

In addition, the amount of silica compound as component (d) is 5-20 parts by mass based on 100 parts by mass of the rubber component. When the amount is less than 5 parts by mass, the effect of improving uneven wear resistance is reduced, while when it exceeds 20 parts by mass, wear resistance and fracture properties deteriorate greatly. From the same point of view, 715 parts in mass are preferred. In addition, silica is not particularly limited, but it can be used by appropriately selecting it from those that are generally used as fillers to reinforce conventional rubber.

For example, wet silica (hydrated silica), dry silica (anhydrous silica), calcium silicate, aluminum silicate and the like can be mentioned. Among them, wet silica is preferred.

In addition, it is preferred that the silica of component (d) has a specific surface area of nitrogen absorption (N2SA) of 120-240 m2 / g. When N2SA is less than 120 m2 / g, wear resistance is insufficient, while when N2SA exceeds 240 m2 / g, a reduced dispersion occurs, resulting in a considerable reduction of low heat accumulation, the resistance to wear and operability in manufacturing.

In addition, the N2SA mentioned is a value measured in accordance with ASTM D4820-93 after drying at 300 ° C for 1 hour.

In the rubber composition used in the tire according to the invention, a hydrazone compound (e) is prepared in an amount of 0.3-3.0 parts by mass based on 100 parts by mass of the rubber component.

When the amount of component (e) is not less than 0.3 parts by mass, the effect of improving uneven wear resistance and heat accumulation is achieved, while when it is not more than 3.0 parts by mass, There are problems in operability.

In consideration of its performance, as the hydrazone compound to be used as component (e) in the rubber composition used in the tire according to the invention, naphthoic acid hydrazide and salicylic acid hydrazide represented, for example, by the following general formulas (I), (II).

image 1

(where R1 and R2 are a hydrogen atom or a hydrocarbyl group having a carbon amount of 1-18, respectively, and can be the same or different, or R1 and R2 can be joined together to form a ring structure. As the hydrocarbyl group with a carbon amount of 1-18, a linear or branched alkyl group having a carbon amount of 1-18, a linear or branched alkenyl group having a carbon amount of 2-18, can be named, cycloalkyl group having a carbon amount of 3-8, an aryl group having a carbon amount of 6-18 and an aralkyl group having a carbon amount of 7-18. In a ring of the cycloalkyl group, you can providing the aryl group or the aralkyl group with an appropriate substituent such as a lower alkyl group, a lower alkoxy group, an amino group, an alkyl substituted amino group, a hydroxyl group or the like.)

As hydrazide compounds of the general formula (I) and (II), 2-hydroxyN '- (1-methyl-ethylidene) -3-naphthoic acid hydrazide, 2-hydroxy-N' - (1-hydroxy acid hydrazide are specifically included -methylpropylidene) -3-naphthoic acid, 2-hydroxy N '- (1-methylbutylidene) -3-naphthoic acid hydrazide, 2-hydroxy-N' - (1,3-dimethylbutylidene) -3-naphthoic acid hydrazide, hydrazide of 2-hydroxy-N '- (2,6-dimethyl-4-heptylidene) -3-naphthoic acid, N' - (1-methyl ethylidene) salicylic acid hydrazide, N '- (1-methylpropylidene) hydrazide -salicylic, N '- (1-methylbutylidene) acid hydrazide -salicylic, N' - (1,3-dimethylbutylidene) -salicylic acid and N '- (2,6-dimethyl-4-heptylidene) acid hydrazide -salicylic.

Among them, 2-hydroxy-N '- (1,3-dimethylbutylidene) -3-naphthoic acid (BMH) hydrazide is particularly preferred.

The hydrazone compound of component (e) suppresses the decrease in the elastic modulus resulting from overvulcanization due to the reversal of natural rubber (a) to control the decrease in low heat accumulation and wear resistance.

By combining the hydrazone compound (e), the modulus of elasticity is raised in a low pressure region in order to suppress the deformation of the rubber tread, thereby preventing the decrease of hysteresis loss at the same time. that the modulus of elasticity in a high pressure region is reduced by the action of silica to ensure elongation of the rubber tread and therefore uneven wear resistance and low heat accumulation can be achieved simultaneously.

In addition, the rubber composition used in the tire according to the invention can be suitably combined with other additives such as sulfur, vulcanization accelerator, processing oil, antioxidant and the like, if necessary.

The rubber composition used in the tire according to the invention is obtained by milling, such as rollers, internal mixers or the like, and is appropriately used as a rubber composition for a tread of a high performance tire that balances widely uneven wear resistance, wear resistance and low heat accumulation.

The tire according to the invention is produced by a usual procedure using the rubber composition mentioned above.

That is, if necessary the rubber composition formed by combining several of the aforementioned additives is molded by extrusion in the form of several parts for a tire in a non-vulcanized state, which are attached to the structure of the tire in the usual manner for Form a raw tire. The crude tire is heated and pressurized in a vulcanization machine to obtain a tire.

In addition, normal air or air having an altered partial pressure of oxygen and an inert gas such as nitrogen or the like can be used as the filling gas of the tire.

The following examples are provided by way of illustration of the invention and are not intended to limit it.

Examples

Several measurements were made using the following procedures.

Evaluations of crude rubber and vinyl bond content of vulcanized rubber in the butadiene portion (mol%): it was measured by infrared spectrophotometry (Morero's method).

Linked styrene content: measured from the intensity of aromatic proton absorption in a nuclear magnetic resonance (NMR) spectrum.

Test tire evaluation

Evaluation of heat accumulation: a drum test is performed under conditions of constant speed and loading in stages to measure a temperature at a position of a constant depth inside the tire, which is represented by an index based on a value of control (Comparative Example 1) of 100.

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The higher the index value, the greater the effect of decreasing heat accumulation.

Evaluation of wear resistance: the wear resistance of a rubber tread on the tire after more than 100,000 km is calculated using an equation [distance traveled / (depth of grooves before travel - depth of grooves after of the path)] and is represented by an index based on the fact that a value of Comparative Example 1 is 100. The higher the value of the index, the better the wear resistance. Evaluation of uneven wear resistance: the tire is mounted on a truck front wheel and used for a travel of more than 100,000 km, after which an uneven wear area is measured and a reciprocal number of the measured value is represented by an index based on a value of Comparative Example 1 being 100. The higher the value of the index, the better the uneven wear resistance.

Production Example 1 (Polymer A)

300 g of cyclohexane, 32.5 g of 1,3-butadiene monomer, 17.5 g of styrene monomer, 0.025 mmol of t-amylate are loaded into an 800 ml glass pressure vessel dried and purged with nitrogen. of potassium and 1 mmol of THF, and 0.45 mmol of n-butyllithium (BuLi) are added to polymerize at 50 ° C for 3 hours. The polymerization system is uniform and transparent without precipitation from the beginning of the polymerization until the end of it. The polymerization conversion is approximately 100%.

To this polymerization system is added 0.12 mmol of 1M cyclohexane solution of DOTDC (dioctyltin dichloride) as a modifying agent to perform the modification reaction for 30 minutes. To the polymerization system, 0.5 ml of a 5% isopropanol solution of 2,6-di-tertiary butyl paracresol (BHT) are also added to stop the reaction, which is then dried to obtain a polymer A. The content of bound styrene is 35% by mass and the vinyl bond content is 23 mol%.

Production Example 2 (Polymer B)

300 g of cyclohexane, 37.5 g of 1,3-butadiene monomer, 12.5 g of styrene monomer, 0.03 mmol of potassium t-amylate and 2 mmol of THF are loaded into a pressure vessel of 800 ml glass dried and purged with nitrogen and 0.41 mmol of hexamethylene imine are added as secondary amine. 0.45 mmol of n-butyllithium (BuLi) are further added to carry out a polymerization at 50 ° C for 2.5 hours. The polymerization system is uniform and transparent without precipitation from the beginning of the polymerization until the end of it. The polymerization conversion is approximately 100%.

To this polymerization system is added 0.09 mmol of 1M cyclohexane solution of TTC (tin tetrachloride) as a modifying agent to perform the modification reaction for 30 minutes. To the polymerization system, 0.5 ml of a 5% isopropanol solution of 2,6-di-tertiary butyl paracresol (BHT) are also added to stop the reaction, which is then dried to obtain a polymer B. The content of bound styrene is 25% by mass and the vinyl bond content is 28 mol%.

Production Example 3 (Polymer C)

300 g of cyclohexane, 32.5 g of 1,3-butadiene monomer, 17.5 g of styrene monomer, 0.025 mmol of potassium t-amylate and 1 mmol of THF are loaded into a glass pressure vessel of 800 ml dried and purged with nitrogen and 0.41 mmol of hexamethylene imine are also added as a secondary amine to polymerize at 50 ° C for 3 hours. The polymerization system is uniform and transparent without precipitation from the beginning of the polymerization until the end of it. The polymerization conversion is approximately 100%.

To this polymerization system is added 0.12 mmol of 1M cyclohexane solution of DOTDC (dioctyltin dichloride) as a modifying agent to perform the modification reaction for 30 minutes. To the polymerization system, 0.5 ml of a 5% isopropanol solution of 2,6-di-tertiary butyl paracresol (BHT) are also added to stop the reaction, which is then dried to obtain a polymer C. The content of bound styrene is 35% by mass and the vinyl bond content is 24 mol%.

The results of the evaluation are shown in Table 1 and the characteristic values of the A-C polymers are shown in Table 2.

Comparative Example 1

Comparative Example 2 Comparative Example 3 Comparative Example 4 Comparative Example 5 Example 2 Examples 3-4 Example Example 5 Example 6

Natural rubber

fifty fifty 40 fifty fifty fifty 40 fifty fifty fifty

Polymer A * 1

- - - - fifty fifty 60 - - fifty

B * 2 polymer

fifty fifty 60 fifty - - - - - -

C * 3 polymer

- - - - - - - fifty fifty -

Carbon black * 4

Four. Five 40 Four. Five 40 40 40 40 40 40 Four. Five

Silica * 5

- 10 - 4 10 10 10 10 fifteen 10

Antioxidant 6C * 6

one one one one one one one one one one

Hydrazone compound * 7

- - - - - one one one one one

Stearic acid

2 2 2 2 2 2 2 2 2 2

Zinc white

3 3 3 3 3 3 3 3 3 3

Throttle

vulcanization

1.2 1.2 1.2 1.2 1.2 1.2 1.2 1.2 1.2 1.2

CZ * 8

Sulfur

one one one one one one one one one one

• Content

of styrene

25 25 25 25 35 35 35 35 35 35

bound

• Content

288 288 288 288 233 233 233 244 244 233

of liaison of

vinyl

Heat accumulation

100 95 94 104 103 108 102 113 113 100

Uneven wear resistance

100 109 112 102 120 128 136 128 146 138

Wear resistance

100 100 100 95 105 105 100 100 102 106

*one. Polymer A: Production example 1, bound styrene content of 35% by mass, vinyl bond content of 23

mol% *2. Polymer B: Production example 2, bound styrene content of 25% by mass, vinyl bond content of 28 mol%

*3. Polymer C: Production example 3, bound styrene content of 35% by mass, vinyl bond content of 24 mol% *4. Carbon black: Seaste 9, trademark, manufactured by Tokai Carbon Co., Ltd. *5. Silica: Nipsil AQ, trademark, manufactured by Nippon Silica Co., Ltd. N2SA (200 m2 / g) * 6. Antioxidant 6C: N-phenyl-N ’- (1,3-dimethylbutyl) -p-phenylene diamine * 7. Hydrazone compound: 2-hydroxy-N ’- (1,3-dimethylbutylidene) -3-naphthoic acid (BMH) hydrazide

* 8. CZ vulcanization accelerator: N-cyclohexyl-2-benzothiazyl sulfenamide Note: with respect to the values in Table 1, the values of natural rubber and A-C polymers are in% by mass, and the values of black carbon, silica, antioxidant 6C, hydrazone compound, stearic acid, zinc white, CZ vulcanization accelerator and sulfur They are in mass parts based on 100 mass parts of the rubber component.

Table 2

Linked styrene content (weight%)

Vinyl bond content (mol%)

Polymer A

35 2. 3

Polymer B

25 28

Polymer C

35 24

Examples 2-6, Comparative Examples 1-5

5 Each composition that has a combination procedure as indicated in Table 1 is ground using a Banbury mixer. The resulting rubber composition is used in a rubber tread to prepare a tire having a tire size of 295/75 R22.5 and then heat accumulation, wear resistance and uneven wear resistance are evaluated by the procedures mentioned above.

As can be seen in the results shown, in high performance tires according to the invention uneven wear resistance is greatly improved while maintaining and improving heat accumulation and wear resistance.

Industrial Application

The invention can provide a high performance tire that greatly improves uneven wear resistance without sacrificing heat build-up and wear resistance.

Claims (1)

1. A high-performance tire that is characterized by using a rubber composition as tread rubber that is obtained by combining 100 parts by mass of a rubber component consisting of 90-30% by mass of (a) rubber natural and 10-70% by mass of (b) styrene copolymer rubber 5 solution polymerized butadiene containing tin in at least one medium potion of the polymer molecular chain and one terminal of the molecular chain and having a bound styrene content of 28-45% by mass and a vinyl bond content in a portion of butadiene less than 30 mol% with 0.3-3.0 parts by mass of (e) a hydrazone compound and 40-60 parts by mass in total (c) carbon black and (d) silica , provided that an amount of (d) silica as a charge is 5-20 parts by mass. 2. A high performance tire according to claim 1, the hydrazone compound (e) is 2-hydroxy-N '- (1,3-dimethylbutylidene) -3-naphthoic acid hydrazide.